Ocaml代写 | CMPS-112 Program 2 Interpreter in Ocaml

1.Overview

This project will repeat the Silly Basic interpreter, except this time the program will be written in Ocaml but with Silly Basic programs untranslated from the original. See the .score/ directory for sample input ﬁles. Output should be the same as for the Scheme version of the program, except for minor variations in output due to differences between the Scheme and Ocaml languages. Any results which would produce a complex value in Scheme should produce nan in this project.

2.Running ocaml interactively

Ocaml may be run interactively from the command line or as a compiled program. The compiled program version, created using make is required for all submitted programs.

To run ocaml interactively, add the following to your $HOME/.bash_profile :

export PATH=$PATH:/afs/cats.ucsc.edu/courses/cmps112-wm/usr/ocaml/bin

To simplify typing, the following line might be added to your $HOME/.bash_profile :

alias ocaml=”rlwrap ocaml”

The suggestions above assume you are using bash as your login shell. If not, use the syntax appropriate for whatever shell you are using.

Some ﬁles that are useful when running interactively are :

using

A set of #use directives which can be used for interactive testing of the functions. This ﬁle is not used in compilation. After starting Ocaml, type in the following command to load your source code interactively :

#use “using”;;

.ocamlinit

As an alternative to the using ﬁle, create the ﬁle .ocamlinit containing the same information. The ﬁle .ocamlinit in the current directory is automatically sourced when ocaml starts.

As an alternative, start up ocaml with the line

rlwrap ocaml -init using

which will start up the init ﬁle when needed, but avoid the automatic startup when you don’t want it. If you have a .ocamlinit and want to ocassionally suppress it,

you can use rlwrap ocaml -init /dev/null

3. Source code

The following ﬁles and modules are provided in the code/ subdirectory :

etc.mli, etc.ml

Interface and implementation of the Etc module, which contains miscellaneous functions not speciﬁcally tied to other purposes.

absyn.mli

Deﬁnition of the abstract syntax used by the interpreter. No implementation ﬁle is needed.

tables.mli, tables.ml

Module for maintaining the ﬁve tables needed by the program. The interface ﬁle is automatically generated from the implemenation, not entered manually. The required tables and their types are :

type variable_table_t = (string, float) Hashtbl.t array_table The arrays used by the program.

type array_table_t = (string, float array) Hashtbl.t

interp.mli, interp.ml

The interface and implementation of the interpreter. This is the major project of this program and must be extensively modiﬁed.

main.ml

The main function which behaves differently, depending on whether the program is run interactively or from the command line. Does the parsing to create the abstract syntax structure, then calls the interpreter.

parser.mly

The parser reads a Silly Basic program, verify syntax, and create the abstract syntax. Speciﬁes the exact syntax of the language.

scanner.mll

The lexical speciﬁcation for the language, and reads tokens from the source ﬁle.

Makefile

Since the Ocaml project is compiled into interpreted bytecodes, a Makefile is needed, as is required in any C, C++, or Java project.

4. What to submit

Submit all of the necessary source ﬁles so that the grader may perform the build. That means submit Makefile, parser.mly, scanner.mll, and all *.mli and *.ml ﬁles. If you are doing pair programming, also submit the ﬁles required by the pair-programming document. Verify the grading criteria from the .score/ subdirectory.